Although the average weight of U.S. citizens continues to dramatically climb, our knowledge and understanding of the medical risks associated with obesity remains limited. Sadly, the increasing incidence of cardiovascular disease associated with obesity (i.e. coronary artery disease, myocardial infarction, stroke and congestive heart failure) promises to damage both our national healthcare system and the lives of many patients. Hence, the overall goal of our laboratory has been to better understand how obesity affects cardiovascular function. Although direct evidence is lacking, recent studies have speculated that adipose tissue surrounding the large coronary arteries of the heart may contribute to the development of atherosclerosis and vascular disease. Importantly, our laboratory has previously documented that this perivascular adipose tissue significantly impairs coronary endothelial function via inhibition of nitric oxide synthase. This impairment is significant because endothelial dysfunction is believed to be the early pivotal step in the progression of vascular disease. Therefore, the current proposed project seeks to delineate the cellular/molecular mechanisms by which perivascular adipose tissue impairs coronary vascular function in obese Ossabaw swine with the metabolic syndrome. Specifically, this project aims to 1) Delineate the mechanism(s) by which perivascular adipose tissue impairs coronary endothelial-dependent vasodilation and 2) Determine the significance and mechanism of perivascular adipose-derived leptin in the development of coronary vascular dysfunction in the metabolic syndrome. To achieve these goals, we propose to assess endothelial function and nitric oxide synthase activity both in vitro with isometric tension studies/measurement of nitric oxide production and in vivo through measurement of coronary blood flow during open-chest anesthetized surgical procedures. Importantly, these experiments will also be conducted in the presence and absence of inhibitors designed to block the activity of kinases known to regulate nitric oxide synthase activity. Furthermore, we propose pnDteomic, immunohistochemical, and additional in vitro isometric tension experiments designed to understand the importance of perivascular adipose-derived leptin in the development of coronary vascular disease. These experiments, in combination with our use of a metabolic syndrome animal model, stand to offer new insight into the importance of perivascular adipose tissue. More importantly, findings from this project will undoubtedly help to advance our overall understanding of the link between obesity and vascular disease.